Programme 5
In the final programme in the series, Jonathan Miller brings the story of reproduction and generation up to the present. He hears first from Nobel prize-winner Sir Aaron Klug who describes the work done by Crick and Watson in 1953 to identify the chemical structure of deoxyribonucleic acid, better know as DNA, which they represented as a double helix.
But as Jonathan argues, since the discovery of DNA, we've had to face up to the enormous complexity of the cellular and genetic mechanisms that enable us to be 'self-made things'.
Lewis Wolpert stresses the importance of the proteins that the genes code for, and the control regions that determine when and where a particular gene is turned on.
Claudio Stern explains how, despite their identical genetic inheritance, dividing cells begin to differentiate and commit themselves to becoming different body parts.
Tim Horder describes Hans Spemann's discovery of a command centre, now known simply as the Spemann Organizer, which sends out signals that inform cells what body parts they should become.
Ever since he was a zoology student, Jonathan has been interested in how many animals, including ourselves, are organised into serial segments. Peter Lawrence explains some of the principles of serial segmentation, and warns Jonathan against assuming that internal genetic segments will necessarily coincide with the external segments that we see with our eyes.
Enrico Coen draws all these threads together in a metaphor that likens our ability to make ourselves to the relationship between a painter and a picture. But rather than there being a distinction between painter and canvas, we have to understand that living things are both painter and canvas. We are the product of an interactive dialogue in which both painter and canvas are interdependent.
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